Motor controller

1. A motor controller, comprising a control system that feedback-controls a moving operation of a moving section provided in a motor through the use of a detected moving amount of the moving section, the motor controller comprising:

a notch filter which is arranged inside the control system and attenuates a signal component of a nearby frequency in accordance with a notch width with a notch frequency put at a center in an input signal;

an oscillation frequency estimating section which estimates an oscillation frequency component in the motor from the moving amount; and

a notch control section which controls the notch filter so as to change the notch frequency and the notch width in accordance with an estimation result of the oscillation frequency estimating section,

wherein, when determining that the oscillation frequency estimated by the oscillation frequency estimating section differs from the notch frequency set in the notch filter, the notch control section changes a frequency between the oscillation frequency and the notch frequency set in the notch filter as a new notch frequency of the notch filter, while changing the notch width to a new notch width such that the notch width becomes larger after the change than before the change.

2. The motor controller according to claim 1 , comprising a plurality of the notch filters,

wherein, when determining that the oscillation frequency estimated by the oscillation frequency estimating section differs from the notch frequency set in each of the notch filters, the notch control section selects out of the notch filters a notch filter in which a notch frequency closest to the oscillation frequency is set, and changes the notch frequency and a notch width of the selected notch filter to the new notch frequency and the new notch width.

3. The motor controller according to claim 2 ,

wherein the notch control section

has a function of switching a state of the notch filter between a valid state and an invalid state,

sets the oscillation frequency as the notch frequency of the notch filter when the notch filter is in the invalid state, and

changes the notch frequency and the notch width of the notch filter to the new notch frequency and the new notch width when the notch filter is in the valid state.

4. The motor controller according to claim 2 , wherein the notch control section outputs an alarm signal when determining that the notch width is not smaller than a prescribed value.

5. The motor controller according to claim 2 , wherein the notch control section stops changing the notch width when determining that the notch width is not smaller than a prescribed value.

6. The motor controller according to claim 2 , wherein the notch control section stops an operation of the motor when determining that the notch width is not smaller than a prescribed value.

7. The motor controller according to claim 2 , wherein the notch control section changes a control gain of the control system so as to decrease the control gain when determining that the notch width is not smaller than a prescribed value.

8. The motor controller according to claim 1 ,

wherein the notch control section

has a function of switching a state of the notch filter between a valid state and an invalid state,

sets the oscillation frequency as the notch frequency of the notch filter when the notch filter is in the invalid state, and

changes the notch frequency and the notch width of the notch filter to the new notch frequency and the new notch width when the notch filter is in the valid state.

9. The motor controller according to claim 1 , wherein the notch control section outputs an alarm signal when determining that the notch width is not smaller than a prescribed value.

10. The motor controller according to claim 1 , wherein the notch control section stops changing the notch width when determining that the notch width is not smaller than a prescribed value.

11. The motor controller according to claim 1 , wherein the notch control section stops an operation of the motor when determining that the notch width is not smaller than a prescribed value.

12. The motor controller according to claim 1 , wherein the notch control section changes a control gain of the control system so as to decrease the control gain when determining that the notch width is not smaller than a prescribed value.